22 
suffering from drought falling to nil. Indeed, a slight but unmistakable 
shortening occurred on certain of the days of observation. ‘The reason 
for this strikingly unequal distribution of the growth is that the active 
transpiration during the day creates an internal scarcity of water and 
reduces the content of that liquid in the plant to such an extent that any 
considerable enlargement is impossible. A similar, but much less pro- 
nounced, daily periodicality of growth is reported for the bamboo,’ 
correlated with the relative humidity. Every factor which contributes 
to the more active transpiration during the day is also in part responsible 
for the cessation of growth."® 
It is a very common practice in Mindanao to plant coconuts and abaca 
together, in the expectation that the abaca will support the commercial 
undertaking until the coconuts mature. This may be expedient, from a 
business standpoint, where the cost of clearing is the chief item in the 
establishment of a plantation; and after the first two or three years the 
coconuts suffer less than the abacd in this competition ; but the maturing 
of the former is delayed by probably two years, and the trees are never 
as robust as those which were better illuminated from the start. The 
ultimate diameter of the trunk of a palm is determined in its youth." 
The heliotropism of the coconut is illustrated by the well-known dis- 
position which trees along the beach have to bend toward the water (fan- 
tastically ascribed to the tree’s love of the sea) and by the tendency of 
those around the outer edges of a grove to lean outward in every direction. 
This heliotropism is the more interesting because the actual growing 
region, where the curving takes place, is deeply seated below the visible 
tip and covered by the bases of many leaves. 
The negative geotropism of the trunk causes a prostrate tree to turn 
upward with a curve the radius of which often does not exceed twice the 
ultimate diameter of the trunk. This abrupt curvature is rendered pos- 
sible only by the harmonious reaction of many growing leaf bases, those 
beneath developing more and those above less rapidly than the ones in 
the middle. Each leaf base executes its own appropriate curve. ‘These 
Lock: Annals Bot. Gard. Peradeniya (1904), 2, 211. Not seen. 
Kraus (Das Liingenwachsthum der Bambusrohre, Ann. Jard. Bot. Buitenz., 
1895, 12, 196), working at Buitenzorg, with almost daily rain, found the diurnal 
retardation of the growth of bamboo slight compared with that reported here for 
Cocos. . 
" At least the larger proportion of the experiments which are supposed to show 
that light exerts a direct retarding influence on the growth of stems and leaves 
are questionable because they do not exclude the possibility of the direct influence 
of the illumination on the transpiration and a consequent indirect retardation of 
growth. While the immediate effect of light is to retard growth, adequate 
illumination is of course eventually indispensable for the healty development 
of the plant. 
“The nuts in a seed bed are usually placed horizontally because the trunks 
grown from such seeds are supposed to be stouter. Drude, in Natiirlichen Pflanz- 
enfamilien, Il, 3, 3, states that some palms, such as Sabal and Ceroxylon, 
normally develop stouter trunks if their earliest growth is horizontal. 
